Snap action mechanism



July 29, 1952 M. L.. JEFFREY SNAP ACTION MECHANISM Original Filed April19, 1947 3 Sheets-Sheet 1 July 29, 1952 M. l.. JEFFREY SNAP ACTIONMECHANISM original Filed April 19. 1947 3 Sheets-Sheet 2 July 29, 1952M. L.. JEFFREY SNAP ACTION MECHANISM Original Filed April .7.9. 1947 3sheets-sheet s Patented July 29, 1952 SNAP ACTION MECHANISM Max L.Jeffrey, Shaker Heights, 0hio original application April 1e, 1947,serial No. 742,578, now Patent No. 2,588,632 dated March Divided andthis application December 15, 1948, Serial No. 65,350

5 Claims.

This invention relates to improvements in switches and switch operatingmechanisms and more particularly to quick acting switches of the snapaction type. This is a division of my co pending application, Serial No.742,578, filed April 19, 1947, now Patent No. 2,588,632.

Although snap action switches have been proposed before and are wellknown in the art, the snap action, if suilcientlyl rugged to vwithstandheavy duty, wascumbersome, complicated and expensive to manufacture. a'

By the present invention, I have provided an improved snap action switchwhich is very compact, simple and positive in operation, inexpensive tomanufacture and is suitable for the most heavy duty in which suchswitches may be utilized.

The snap action is also` particularly useful in conjunction with a`multiple contact circuit breaker andas such will vbe described inconjunction therewith. AvIt will-ber appreciated that it is useful forcommunicating a snap action to other 'types of circuit breakers,however, and therefore is/not limitedin its use to the par- .ticulartype shown and described.

In a multiple circuit, it is essential in many instances that the'switchbe designed to provide some circuits which are closed while othercircuits are open. This makes it necessary, in each such circuit,v todesign or obtain a switch adapted for that particular use. Eventually,in the case rof complicated ormultiple circuits, it becomes necessary todesign special switches for those. circuits which are not ordinarilyuseful excepty for that particular job. This increases the expense aswell as delays the entire installation while the switch is beingprocessed.

By my Present invention I` have provided a switch where the componentsare such that they may be added to orr subtracted from the assembly toprovide a switch for as many circuits as is desired. Furthermore, thecomponents are such that by the. mere reversal of certain componentsthereof, a switch is provided which opens or closes a circuit. Thus, aswitch is provided which may open or close simultaneously any desirednumber of circuits without the necessity of special design.

Another advantage of the construction is that, should. the load throughone section of the switch be more than through another section causingthe contacts in the heavy load section to wear, a new section can besubstituted quickly and easily, and it is not'necessary to` otherwiserenew the entire switch. Furthermore, one section which wears, due toarcing, more than the other, may have the points dressed down andsubstituted for another sectomkwhere the wear has not been so largebecause of the reduced load. Thus, as time goes on, the sectionsV may berotated until eventually they are all worn out simultaneously.

Still other advantages of thek invention and the invention itself willbecome more apparent from the following description of an embodimentthereof, which description is illustrated by the accompanying drawingsand forms a part of this specification.

In the drawings:

Fig. 1 is a full size plan view oi a switch enrbodying my invention;

Fig. 2 is a frontend elevational view thereof;

Fig. -3 is a section taken on the line 3-3 of Fig. 1;

Fig. fi is a rear elevational view thereof;

Fig. 5 is a vertical medialv section through the switch;

Fig. 6 is a side elevational view of one of the levers which go to makeup the snap action mechanism; p

Figs. '7 and 8 are sections taken on the lines Figs. 9 and 10 are frontand side elevational views respectively on another lever whichcoopcrates with the lever shown in Fig. 6 in making up the snap actionmechanism;

Figs. 11 and 12 are side and end elevational views oi the support kforthe levers. of Figs. 7 and 9;

Figs. 13 and 14 are side and elevational views respectively of aconnector coupling for connecting the snap action mechanism and theswitch assembly;

Figs. 15 and 16 are iront and side elevational views of a switch rotor;

Fig. 17 is a plan view of a contact carrying strip and its contacts;

Fig. 18 is an edge view thereof with part broken away and shown insection;

Fig. 19 is an end elevation of the switch with one of the front platesremoved to show the snap action mechanism;

Fig. 20 is a plan View of a switch Showing an alternate form of assemblyand with certain parts broken away to show'a plan view of the snapmechanism;

Fig. 21 is a section taken on the line 2l -21 of Fig. 20, with certainof the parts shown in side elevation; and

Fig. 22 is a of Fig. 20.

The mechanism about to be described is illustrated as being without ahousing. 'It will be appreciated., however, that a housing iscontemplated, although there may be cases, where the switch is used in.conjunction with other apsection taken on the lines 21'2--22 paratus,where the housing for such apparatus will also house the assembly.

Likewise the switch is operated by a rocking or rotating shaft but noparticular means is shown connected to the shaft for effecting suchrocking or rotation, since this can be effected in many ways as by anelectrically operated solenoid, hydraulically or mechanically,

Briefly, the embodiment of my invention shown contemplates a snap actionmechanism'whereby a turning movement of a shaft causes a certain amountof kinetic energy to be built up in the mechanism which is released at apredetermined time to cause the quick snap rotary action which iscommunicated to the movable contacts through a coupling.

The circuit breaker. portion of the switch includes pairs of fixedcontacts and movable contacts which are moved into and out of engagementtherewith. Each set of contacts, for oontrolling a single circuit ishoused in a separate housing, and by merely turning one of the housingsend for end, thatA circuit can be normally open or closed. There isnolimitation on the number of housings and their elements that can beused. Therefore, a switch can be fabricated for any particular job withthe same parts, all as will heretofore more clearly appear.

As can best be seen in Figs. 1 to 3 inclusive, the snap action mechanismincludes a rectangular base plate I having a pair of outwardly extendingbosses II at its upper end. A pair of bosses I2 are also provided spacedfrom the bottom edge of the plate and the upper bosses. Intermediate thetwo upper bosses I I is a circular boss I3'. The bosses I2 are providedwith outwardly extending pins I4 for engagement in apertures in a frontplate I6, and they are also provided with threaded apertures, whichtogether with the threaded aperture in the boss I3 are adapted toreceive screws I5 which hold a front plate I6 in position. The pins I4enter into holes in the plate and properly locate the'same, and thefront plate is thus held in spaced parallel relation to the back plate.The front plate is of generally rectangular form being provided with anupwardly extending portion I8 which extends between the bosses I I.

The base plate is provided with an opening 20 in its mid-section, theopening being reinforced by an annular boss 2I on the rear thereof whichextends around the opening, the opening through the plate and the bossconstituting a bearing for the coupling shown in Figs. 13 and le.

The coupling comprises a barrel 23 rotatably journalled in the opening20 and is provided with a projection 24 which extends rearward of theplate and is vertically slotted at 25. The slot provides means forconnection with the switch rotors or tumblers later described.

The coupling is provided with a flange 2S adapted for engagement withthe front of the base plate I0 and a circular projection 21 whichprovides a bearing surface for the lever illustrated in Fig. 7. Thebarrel of the switch is provided with an axial bore 28 to provide abearing for the operating member (Fig. 11) and is slotted horizontallyat 29.

The operating member includes a pivot pin 30, adapted to be rotatablyjournalled in the bore 2S of the coupling, and a cylindrical body 3|rotatably journalled in an opening in the front plate. A flange 32 isprovided, which engages with the back of the front plate and is heldthereby in position. The body 3I is provided with longitudinallyextending slots 33 which extend the length of the body on opposite sidesat its diameter and also across the end which projects beyond the frontplate, adapted to have an operating member, not shown, secured thereto.

Movement from the operating member is transmitted to the connectingmember by a snap mechanism supported in part by the two members and inpart by the front and back plate. This mechanism includes the two leversof Figs. 6 to 8 inclusive and Figs. 9 and 1I). The lever of Fig. 9 isprovided with a ring shaped body 40 having inwardly. extending tongues4I adapted to engage in the side slots 33 of the operating member.

Extending upwardly from the body is a neck 42 which carries on its end ahead 43 having two slanting cam faces 44. This lever is adapted to beswung together with the operating member, the ring 40 being disposed onthe body of the operating member, with the tongues 4I extending into theslots 33. p

The second lever, as best shown in Figs. 6 to 8 inclusive includes twovspaced apart members adapted to be disposed on opposite sides of thenrst lever. The one part includes a ring shaped body 50 which isrotatably journalled on the body 3l of the operating member adjacent therear of the ange 32. It likewisehas a neck 52 extending upward and whichcarries a head 53 on its end. The other part of the member is of thesame conformation, except that the ring 50 is provided with inwardlyextending tongues 54 and is adapted to be disposed over the part 21 ofthe connector member with the tongues 54 engaged in the slot 29. The twoportions of the second lever are held together in spaced relation bypins 55 the ends 5'I of which are oi reduced cross section and extendthrough openings'in the heads 53 and are headed over to hold the same inplace.

The head 53 is of generally T-shape, the extremities extending downward.The mid portion 59 is arcuate and is provided with two steps or notches60 equally spaced from the center and spaced from the end, forengagement with pawls as will later appear.

It will thus be seen that the first lever 40-44 is xed on the operatingmember 30-33 and the second lever 50-60 straddles the nrst lever,rotates freely on operating member but has a driving connection with theconnector 23-29.

Spring means is provided for transmitting movement from the first leverto the second lever and hence from the operating member to the couplingmember and comprises a C-shaped spring 62 of appreciable width, the endsof which engage with all of the necks 42 and 52 of the two levers. Itwill thus be seen that the movement from one lever to the other istransmitted throngh the spring and that should either one of the leversmeet with any resistance which would tend to hinder its movement theother lever can continue to move, the ends of the spring merely beingpushed apart.

It is by virtue of this action that the snap action is obtained. This iseiected by holding the second lever against movement until apredetermined relative movement between the two levers is obtained and apredetermined amount of spring pressure is built up at which time thelever is released, and the spring, the ends of which are pressed againstthe misaligned necks, snaps the two levers into alignment.

The bosses II are provided with downwardly extending portions 65 inwhich are disposed pins Eextending outward from the plate and-.on whichare iournalled paw-ls 6T which include a body of generally rectangularform, the ends of which are biiurcated at G3 to provide a yoke in whicha roller GSi/is disposed on a pin '.'ilA extending through the arms ofthe yoke.

The roller SSextends between the spaced' apart headv portions 53 of thelever`560 while the body of the pawlli'fis of sufficient width'to bridgethese portions. Helical springs 'H are" provided rfor urging the pawlstoward the surfaces ligand notches t6, having one end' seated in arecess T2 in the pawl andthe other end in engagement with the slantingsurface T3 on the boss 65.

In operation the two levers are normally held in alignment by the spring62 which, asr stated, engages with the necks. The lever 40.--44 isswungwhen the coupling Sal-33 is rotated but' the lever Ele-53 is heldagainst movement by one of the pawls Si?, the end of which engages inone of the notches Gill on the periphery ofV tllelTv shaped head. Theresult is that although the center lever is moved, the outside lever'stands still and thenecks on the two levers which are then swung out ofalignment force the ends of the spring 62 apart. The further out ofalignment the tw-olevers move, the greater the tension built up in thespring.

:is the lever iB-lf3 is swung farther, one of the cam races 44eventually engages the roller ES. on the pawl forcing the pawl upwardvagainst the pressure of the spring 'l I. The pawl is thus eventuallyforced out of engagement with the notch tu and releases the outside'lever 5ll-53. At this time the spring which has had the ends pushedapart and is exerting considerable pressure against the misaligned necksof the two levers, snaps the two levers quickly into alignment. Theoutside lever then swings to the opposite position to that shown in-Fig. 2 and the other pawl is engaged in the other notch 66.

The spring 52 can be a single C shaped spring, or it can consist oiseveral springs placed on top of each other. Springs may beadded orremoved or stiffer springs may be substituted to provide substantiallyany tension desired.

The tongues 54 on the outside lever being engaged in the notches 29 'ofthe coupling 23-28 which is j ournalled in the base plate, the couplingis quickly rotated, which movement is communicated to the switch rotoror rotors.

As previously1 stated, the snap' action mechanisw is adapted" to movethe switch rotors to r y open or close the contacts. vPreferably, ea irotor is disposed in a separate housing, and :le housings be securedtogether with the rotor one housing in interlocking engagement with theother to thus enable all of the rotors to be operated in unison.

Each of the housings may be comprised of a suitable insulating material,preferably such as be readily molded and is not subject to distortion ordeformation in the presence of heat.

is best shown in 3 and 4, each housing has a body or sidewall 'i5 inwhich a recess 'I6 is formed, the recess being of suitable conformationto house the rotor Tl which is capable of limited movement therein.rl'he one end of the recess is closed by a wall 18 which is apertured at'i9 to provide a bearing ksurface for the hub 8B of the rotor.

The terminal strips 8| are provided having one end disposed in recessesEl opening to the exterior of the housing, and extending through thewall to the interior as indicated at B2. The interiorly extending partof the strip is backedby a boss 83 on the housing, andcarries a fixedcontact 84, the strip being so arranged that the contact is in thepathof travel of 'the movable contact carriedby the rotor. If desired, theterminal strips 8| may bev secured in the housing during the moldingoperation.

The end of the strip in the recess may beprovided with one or.moreterminal screws 85. The base plate l0 isA provided with rearwardlyextending bosses 8l, one of which is oppositer to the post I3, and the.othertwo. are disposed at the n lower end of the plateadjacentoppositecorners. rI he bosses are provided with threadedopenings for the reception of' screws 88. which extend through bertubes` I3J0V disposed in openings 89 in the housings. Thus a series ofhousings may be secured to the base plate 1.9.

The rotors which carry the movable contacts each comprise a hub 800icylindrical form, which, as stated, is journalled in the wall of thehousing and is provided with a tongue 90 on one end adapted to extendinto and engagev the walls of the slot of the` couplings 2'3-29 toprovide an operating connection therebetween. or, as will later appear,the tongue may engage in the slot of another rotor.

It should be noted, as can best be seen in Fig. 5, that the bearingsurface doesnoti extend entirely through the wall butterminatessubstantially half way through the wall.v

The other end of the hub extends outward and A housings` cooperatesvwith the other housing and that one housing acts as a. closing wall forthe other housing. It: will al'soappearthat in a oase where all thehousings face in the same direction, the last housing would be` open andits rotor unsupported if it were not for the fact that the housing canalso be closed by a single plate which has an opening 96 in which thehuby of the rotor is journalled. This is shown clearly in Fig. 5 wherethe plate S5 is utilized to provide a wall between the second and thirdsections, or in Figs. 20 and 21 where the plates are used to separatethe housings.

At this point it should. be noted that in some instances it maybefd'esirable to make each of the housings in two parts, in which eventthe wall portion T8' of the housingl would be open on both sides andonly comprise the parts extending from the wall. This is shown clearlyin Figs. 20 and 21.

.Each rotor is also provided with a pair of curved arms 98' which extendoutwardly from diametrically opposite sides of the hub and are providedwith flat faces 99, Figs. l5 and l5 having circular bosses IUD whichextend inopposite directions and toward a horizontal line through thediameter oi the hub but spaced therefrom. The hub is formed with a slot|.0'2 which extends transversely of the hub along they horizontaldiameter thereof and the walls 83 which diverge slightly from the centerof the hub toward the periphery.

A contact carrying strip is provided for the hub and includes a flat bar105, adapted to rotate freely in the slot I2 and capable of relativemovement between the walls thereof. The mid section of the bar isprovided with a tongue H35 adapted to extend into and having a bearingin a circular recess Ill?! in the axis of the rotor hub and opening inthe bottom of the slot i D2.

The ends of the contact strip are enlarged at |08 and have securedtherein in any suitable manner, as by riveting, the contacts |09, Figs.17 and 18. Preferably, the Shanks of the contacts extend through theportions |08 and are headed over at to provide a boss for retaining ahelical spring in place, the other end of the spring being disposed onthe boss |00. Thus, the springs tend to hold the contact strip rotatedin a counter clockwise position as shown in Fig. 3 with the sides of thestrip in engagement with the walls |03 on opposite sides of the axis ofthe rotor.

When the contacts are closed, as shown in Fig. 4 upon the rotary contactmeeting the xed contact, further rotary movement of the contact strip isprevented, but the rotor may continue its rotation relative to the stripwhich pivots about the tongue |06, the springs |I compressing and thesides of the strips moving away from the walls |03. Thus, in the contactclosed position the contacts are held in spring pressed engagement withthe fixed contacts.

It will be noted from Figs. 1 and 3 that the snap action mechanism is inits left hand position, and that to operate it the operating member53E-33 must be moved in a clockwise direction. This movement iscommunicated to the rotor which is also moved clockwise as viewed fromthe right and of Fig. 1 or counter clockwise as viewed in Fig. 3 tocause the closing of the contacts.

This is true of the rst and second sections of the switch as viewed inFig. l, but it will also be noted that the third and fourth sections areturned around; that is, turned end for end so that they face in theopposite directions to those of sections one and two. In this case, theplate 95 is disposed between the two sections, and as can be seen inFig. 5, since the hubs of the rotors, which have slots |20, which alignwith the tongues 9|) on the opposite end and are normally disposed forengagement with the tongues on the adjacent rotor (Fig. 5) are towardeach other, a coupling member |2| in the form of a fiat rectangular bar,which may also be insulating material, is disposed in both slots |20 ofthe adjacent rotors connecting them together.

The remaining or end section is also turned around. Therefore, thetongue and groove connection therebetween is provided.

It will be seen therefore that sections one and two have the contactsopen, and that sections three and four (Fig. 4) have the contactsclosed. Therefore, when the snap action mechanism is operated, the opencontacts close, and the closed contacts open.

It will be appreciated that by this arrangement any number of sectionscan be built up to provide a single contact for the desired circuit, andwherein simultaneous opening and closing of circuits is attained.

I have described the sections as being held together with a screw 88which extends through aligned openings in the discrete sections. Thereis also shown a fiber tube |30 which is first inserted in the openingsand subsequently the screw extends through the tube. This constructionincreases the dielectric path and prevents arcing to the bolt.

In Figs. 20 and 21 I have shown a three-section switch wherein the sidewall sections are separated from the end walls.

In this case the contact carrying strips 8| are somewhat narrower thanin the other design and are secured in place during the molding. In allother respects, however, it is the same as that of Figs. 1 to 5inclusive.

As can best be seen in Fig. 19, the ends of the lever 50--60, at thelimit of their movement are closely spaced to the top surface of thelower bosses |2.

This spacing is maintained by the springs on the contacts which in theclosed position are under compression. The end of the lever may contactwith the bosses |2 limiting the movement and removing strain from therotors in event that the operating member has a tendency to over travel,causing a further relative movement of the snap action levers. It willbe apparent that considerable over travel is allowable because of thisconstruction without undesirably affecting the operation.

It will therefore be clear that the snap action is small, rugged, simpleand economical to manufacture, and that it takes up a minimum of spaceallowing a compact assembly to be made. It is also apparent how theswitch assembly per se is versatile, enabling a few standard parts to beused and allow the fabrication of a switch which can control a greatvariety of circuits.

Having thus described my invention, I am aware that numerous andextensive departures may be made therefrom without departing from thespirit or scope of my invention.

I claim:

1. A snap mechanism comprising first and second coaxially alignedrotatable shaft sections movable relative to each other, a driver membercarried by the first section and a driven member carried by the secondsection and spring means connecting the driving and driven members,means for holding the driven member against movement including pawls forengagement with the driven member, said driven member being formed witha slot extending longitudinally thereof and a curved surface concentricto the shaft axis having spaced apart notches for alternate engagementwith said pawls, said pawls having portions resting on said curvedsurface and other portions extending alongside said driven member intosaid slot and in the path of travel of the driver member, said drivermember being arranged to engage said last mentioned parts of the pawlsand raise them alternately in said slots to disengage said pawls fromsaid notches.

2. A snap action mechanism including a driven member and a drivingmember, means to connect said members whereby a slow rotary movement isconverted to a fast rotary movement including a driven lever connectedto said driven member and comprising a pair of spaced apart membersrigidly connected to each other, a driving lever connected to saiddriving member and disposed between the spaced members of the drivenmember, spring means for holding said driving and driven members inpredetermined position relative to each other adapted to have itstension increased upon relative movement between the levers, said drivenmember having a portion formed with spaced apart seats, separate pawlmeans disposed for engagement with said seats, and means carried by eachpawl extending between the spaced apart elements, and means on saiddriving lever for alternate engagement with the means carried by eachpawl to move said pawl out of engagement with said seat upon apredetermined movement of the driving member, said spring adapted tomove the driven member upon relays of the pawl.

3. An apparatus of the class described including an operating membercomprising a slotted barrel, a reduced extension on said barrel, adriving lever having a ring disposed on the barrel and provided withtongues extending from the inside of the ring into the slots, a neckextending from the ring and a head on the end of the neck formed withcam faces on the end of the head, an operated member journalled on thereduced extension at one end and supported in a bearing on the otherend, a driven lever having a ring portion rotatably journalled on saidbarrel and disposed on one side of the driving lever and a second ringportion disposed beyond the end of the slotted barrel and the other sideof the driven lever, tongues extending inwardly from the ring in thesecond portion and engaging in grooves of said operated member, saiddriven lever having necks extending therefrom in spaced axial relationto each other on opposite sides of the neck on the first lever, cammembers carried by said necks on the ends thereof and swingable onopposite sides of the driving lever, means rigidly connecting said cammembers together at their ends, spring means for drivingly connectingsaid levers together disposed around said rings and engaging said neckson opposite sides, latch means for said second lever, said cam memberson the driven lever having a curved intermediate portion and formed withlatch engaging shoulders at the end of the intermediate portion, saidlatches being pivotally journalled and swingable into and out ofengagement with said shoulders, and means on said latch comprising aroller extending between said cam members adapted for engagement by saidcam faces on the head of the driving lever, spring means for holdingsaid latches against said cam faces and for urging said latchesalternately into said notches, said rst cam upon being swung beingalternately engageable with the rollers on said latches and said drivenlever being movable by said spring upon release of one latch andengageable upon said movement by the second latch to hold the same inalternate locked positions.

4. An apparatus of the class described including an operating membercomprising a slotted barrel, a reduced extension on said barrel, adriving lever having a ring disposed on the barrel and provided withtongues extending from the inside of the ring into the slots, a neckextending from the ring and a head on the end of the neck formed withcam faces on the end of the head, an operated member journalled on thereduced extension at one end and supported in a bearing on the otherend, a driven lever having a ring portion rotatably journalled on saidbarrel and disposed on one side of the driving lever and a second ringportion disposed beyond the end of the slotted barrel and the other sideof the driven lever, tongues extending inwardly from the ring in thesecond portion and engaging in grooves of said operated member, saiddriven lever having necks extending therefrom in spaced axial relationto each other on opposite sides of the neck on the rst lever, cammembers carried by said necks on the ends thereof and swingable onopposite sides of the driving lever, means rigidly connecting said cammembers together at their ends, spring means for drivingly connectingsaid levers together disposed around said rings and engaging said neckson opposite sides, latch means for said second lever, said cam memberson the driven lever having a curved interme- 10 diate portion and formedwith latch engaging shoulders at the end of the intermediate portion,said latches being pivotally journalled and swingable into and out ofengagement with said shoulders, and means on said latch comprising aroller extending between said cam members 'adapted for engagement bysaid cam faces on the head of the driving lever, spring means forholding said latches against said cam faces and for urging said latchesalternately,7 into said notches, said rst cam upon being swung beingalternately engageable with the rollers on said latches and said drivenlever being movable by said spring upon release of one latch andengageable upon said movement by the second latch to hold the same inalternate locked positions, abutments disposed for engagement with theends of the driven member for limiting the movement thereof.

5. A snap action mechanism comprising rst and second rotary members inaxial alignment, driving members connected to one of said rotary membersand a driven member connected to the other, said driven membercomprising a pair of rigidly connected spaced apart portions one ofwhich is rotatably journalled on the first rotary member and the otherof which is rigidly connected to one other member, said driving memberbeing drivingly connected to said first rotary member and disposedbetween the spaced apart portions of the driven member, said membersbeing provided with radially extending portions the lateral edges ofwhich coincide, spring means engaging with said lateral edgesundertension for holding said radially extending portions in alignment witheach other adapted to increase in tension upon relative movement of saidmembers, said driven members extending beyond the end of the drivingmember and provided with the ends extending laterally from said radiallyextending portions in the directions of travel of said member, saidlaterally extending portions being provided with spaced apart notches,separate pawl means each disposed for alternate engagement in saidspaced apart notches upon said driven member being moved topredetermined position, rollers carried by said pawls and extendingbetween said spaced apart portions, said driving lever having a portionmovable into alternate engagement with each of said rollers to forcesaid pawls out of said notches.

MAX L. JEFFREY.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 17,304 Knaak May 7, 1929665,514 Ely Jan. 8, 1901 1,945,819 Millermaster Feb. 6, 1934 1,979,277McLoughlin Nov. 6, 1934 2,262,306 Thompson Nov. 11, 1941 2,270,951Jeffrey Jan. 27, 1942 2,319,503 Glogau May 18, 1943 2,352,815 VanValkenberg July 4, 1944 2,395,572 Meurer Feb. 26, 1946 2,453,161Schleicher Nov. 9, 1948 2,468,551 Goff Apr. 26, 1949 FOREIGN PATENTSNumber Country Date 498,439 Germany May 24, 1930

